Excavator tooth driving apparatus



' ited tates [72] Inventor John E. Holder 2,605,748 8/1952 Rasoletti 92/13X Dallas, Tex. 2,770,056 11/1956 Hawkins 37/2 [21] Appl. No. 742,561 3,216,510 11/1965 Briden 173/15 [22] Filed July 5,1968 3,305,953 2/1967 Von Mehren et a1. 37/142 [45] Patented Dec. 29, 1970 [73] Asslgnee oncqmpany Primary ExaminerErnest R. Purser lladelphla, Pa. a cor oration of New Jerse Attorneys-George L. Church, Donald R. Johnson, Wilmer E.

p y McCorquodale, Jr. and John E. Holder [54] EXCAVATOR TOOTH DRIVING APPARATUS 7 Claims, 8 Drawing Figs.

[52] U.S. Cl 299/67, BS h particular embodiments described herein as 37/ 1421 172/ 7771 299/70- 299/94 illustrative of one form of the invention utilize an apparatus [51] ll'ft. for imparting a jarring force to an excavator in order to break [50] Field of Search 299/67, 69, or dislodge unusuany hard material within the material being 139, 190,159,871 172/38, 53, 777; excavated. First sets of excavator teeth are movable under ex- 188/86, 88; 175/297; 92/13 treme load conditions to a recessed position permitting a second set of teeth to impose a jarring impact to hard materi- [56] References cued als imposed by a jarring operation. The first sets of teeth UNITED STATES PATENTS designed for normal excavating operations are protected from 1,804,700 5/1931 Maxwell 175/297 the full load of the jarring impact by movable wear plates.

as \M 'L\ 62 \la PATEN TF.[]UEC29|97O 3550.960

182 FIG. 5A

9o FIG 4 QB INVENTOR JOHN E. HOLDER FIG. 6 FIG. 7

ATTORNEY EXCAVATOR TOOTH DRIVING APPARATUS BACKGROUND OF THE INVENTION This invention relates to an apparatus for excavating earth materials and more particularly, to an apparatus for excavating hard materials from earth formations.

A problem associated with the excavating or mining of earth materials is the wear and breakage of earth contacting portions of the excavating equipment, which, for example, may be in the form of bucket teeth. Wear is normally the result of abrasion and impact with earth materials being excavated. An example of this problem involves the mining of bituminous tar sands. The sands are composed of a silicous material, generally having a size greater than that passing a 325 mesh screen, saturated with a relatively heavy viscous bitumen in quantities of from five to 21 weight percent of the total composition. The bitumen is quite viscous and contains typically and contains typically a 4.5 percent sulfur, and 38 percent aromatics. A specific gravity at 60 percent F., ranges typically from about one to about 1.06. The tar sands also contain clay and silt in quantities from one to 50 weight percent of the total composition. Silt is normally defined as mineral which passes a 325 mesh screen, but which is larger than two microns. Clay is mineral smaller than two microns, including some silicous material of that size. The composition described, together with the peculiar consistency due to its viscous nature, has been found to exhibit extreme wear properties on equipment normally used for excavating earth materials. Therefore it is desirable, in the design of such equipment, to use materials which exhibit good wear properties in such an environment. However, layers of hard rock material are often encountered in the formations containing the tar sands. Also, boulders or large rock masses are found embedded in the tar sands. Due to the encountering of such hard materials, it is costly to use some materials in the construction of excavating equipment which might otherwise be applicable, because of their wear properties. For example, tungsten carbide bucket teeth exhibit desirable wear properties for excavating the abrasive tar sand material, but are not compatible with the excavation of hard rock, because of the brittle nature of tungsten carbide.

The present invention is therefore directed to an apparatus for mining earth materials and in particular, tar sands under the conditions described above. In its most specific embodiment, the invention is disclosed with a bucket wheel excavator for mining the tar sands. However, the apparatus disclosed would have application to a variety of excavating techniques employed with a variety of earth materials. Regardless of the particular excavating apparatus utilized for mining earth materials, continuous contact between an excavating member and earth materials causes a great deal of wear on the members. It is proposed by the present invention to reduce this wear, and to provide a means for breaking up hard layers of materials encountered within the particular material being excavated. In mining tar sands, as with other materials, the excavator is often mounted on a wheel, with the wheel being rotated to force the bucket teeth or blades into the earth material, such as tar sand deposits, to carry the sands upwardly, and to discharge the sands by gravity adjacent the top point of the bucket rotation. Continuous contact between the bucket teeth or blades and the deposit wears the teeth to a point where they are no longer of service and must be replaced. The wearing process is accelerated during winter operations, when the deposit faces are frozen and extremely hard. When lenses of hard formation or boulders are encountered, often times the wheel cannot be stopped in time to prevent the teeth from breaking, which in turn causes a shutdown of the excavator for the purpose of replacing the teeth. Such a shutdown of excavators is extremely expensive. Some idea of the expense is obtained by considering the size of a bucket wheel excavator, which, for example, is being used in the mining of tar sands. These particular excavators are 100 feet high from the bottom treads of their caterpillar crawlers LII tooth having a hydraulic mechanism and embodying princito the top of their bucket wheel riggings. They are about 2l0 feet in length and weight about 1,700 tons each.

It is therefore an object of the present invention to provide a new and improved apparatus for excavating materials containing hard substances.

SUMMARY OF THE INVENTION The present invention contemplate an excavator in the form of a shovel or a bucket wheel, which has a set of teeth for digging the material to be mined. Means are provided on the bucket for imparting a jarring blow to the hard materials when they are encountered. In one embodiment of the invention, the teeth themselves are comprised of, generally speaking, two different types for digging earth materials exhibiting dissimilar physical properties. One of the types of teeth has a resilient means located beneath the teeth which permits its recession into the bucket housing in the event the material encountered is hard enough to force the tooth downwardly against the resilient means beneath the tooth. The second type of teeth, which are recessed downwardly from the first resiliently mounted teeth, are nonmovably mounted within the excavator housing, and are preferably made of a different material, having properties which are more compatible with the harder material being mined. In addition, one of the resiliently mounted teeth also includes in its structure, a release system in the form of a delay device, which permits recession of the tooth at a rate equal to or slower than the other spring loaded teeth, but which upon receding a predetermined amount, has a mechanism which permits its fast release or recession within the excavator housing. This in turn permits a jarring impact of the second set of teeth with the hard material encountered. This release system has provisions for fast resetting, so that the jarring control mechanism is rapidly restored to its initial position for subsequent operations. In addition, means are provided on the apparatus for preventing the second set of recessed teeth from normally encountering the earth materials being excavated, yet permitting such teeth to be exposed when the bucket encounters a relatively hard substance within the material being excavated.

A complete understanding of this invention may be had by reference to the following detailed description, when read in conjunction with the accompanying drawings illustrating embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an excavator bucket wheel;

FIG. 2 is an isometric view of the excavator bucket for mounting on the bucket wheel;

FIG. 3 is a cross-sectional schematic drawing of a bucket ples ofthe present invention;

FIG. 4 is a detailed perspective view of an adjustment feature of the hydraulic mechanism of FIG. 3;

FIGS. 5A and 5B are schematic illustrations of an apparatus for protecting bucket teeth; and

FIG. 6 and 7 are schematic cross sections of an alternative embodiment of the apparatus shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, FIG. I shows a side view ofan excavator wheel 12 mounted on a boom 14. This structure forms a part of an excavator apparatus, the remainder of which is not shown for the sake of simplicity. However, such apparatus normally would consist of a support structure adapted to rest on the ground, a turntable structure having a turning axis, and rotatably supported by the support structure, the working boom connected at one end of the turntable structure and projecting outwardly therefrom, and the bucket wheel 12, which is rotatably mounted at one end of the working boom 14. The support structure is normally mounted on wheels or tracks for moving the structure relative to the material being excavated. The apparatus also may include a conveying mechanism for moving earth materials excavated by the buckets to a location adjacent to the excavator for removal. The bucket wheel is comprised of a circular frame 16, rotatably mounted at the end of the boom, with buckets 18 having teeth 34 extending substantially outwardly from the periphery of the bucket for severing earth material as the bucket wheel is brought into a position for contacting the face of an exposed earth formation.

As shown in FIG. 2, a conventional bucket is generally V- shaped when viewed from the side, and consists of a solid arcuate backwall 22, solid sidewalls 24, and a cutting lip 26 at the leading edge of the back and sidewalls. The lip of each bucket projects beyond the wheel rim, and the lower end of the bucket extends slightly inwardly from the rim ofthe wheel. The excavator bucket or shovel has teeth mounted along the front and side lip thereof. Selected teeth 28 are mounted in a housing 30 with springs 32 positioned between the lower end of the teeth and the bottom of the housing. The remainder of the teeth 34 are stationarily mounted on the bucket. The stationary teeth are normally covered by a projecting shield 36 shown partially in dotted lines in FlG. 2. The protecting device will be described in detail in conjunction with the apparatus shown in FIGS. A and 58.

Referring next to FIG. 3 of the drawings, a hydraulic mechanism is shown for permitting recession of the center tooth 38 under controlled conditions. The mechanism includes a housing 39 for slidably receiving a rod or mandrel 40 extending from the lower end of the tooth, which rod forms a piston rod in the hydraulic mechanism. A shoulder 49 forms a closure at the upper end of the housing and has an opening for receiving the mandrel 40. An O-ring seal 42 is positioned within the opening in the housing shoulder to provide a fluid sea] at the upper end of the housing, which in turn forms a hydraulic chamber 46 in the housing below the seal. The interior bore of the housing has a shoulder portion 50 formed therein which provides a small diametered bore 52 within the housing bore 44. The mandrel 40 which extends downwardly from the lower end of the tooth has an enlarged portion which forms a piston 56 thereon. The piston is sized in diameter to provide a restricted fluid flow between the shoulder portion 50 and the exterior surface of the piston 56 which permits a controlled rate of fluid flow between the piston and shoulder. Passageways 58 are formed longitudinally through the piston and communicate its lower and upper ends. A check valve 60 is positioned in each of the passageways which permits fluid flow through the passage in a downward direction, but prevents flow in an upward direction. A compression spring 62 is positioned between the lower end of the piston and the bottom of the hydraulic chamber. An annular sleeve 54 is threadedly received within the upper end of the small diametered bore. The sleeve is longitudinally movable within the bore by rotating the sleeve. The lower edge of the sleeve forms a limit stop to the upward travel of the piston. Details of the sleeve 54 and piston 56 are shown in FIG. 4. The upper portion ofthe sleeve has an exterior threaded portion 55 for engaging threads 57 in the small diametered bore 52 at the upper end of the hydraulic chamber. A recessed lower portion 59 of the sleeve is constructed without threads and is slidably received within the small diametered bore 52 of the hydraulic chamber. A pair of laterally unaligned keys 66 are formed on the lower surface 63 of the sleeve and are positioned on opposite sides of the sleeve rim. A pair of complimentary keys 65 are formed on the upper surface of the piston 56 and are arranged to be positioned adjacent the keys 66. The mandrel 40 is not shown in H0. 4 so that the keys may be more clearly seen. The keys 65 and 66 provide an interlock between the piston 56 and sleeve 54 so that rotation of mandrel 40 and piston 56 is transmitted to the sleeve 54. in this manner the longitudinal position of sleeve 54 may be adjusted to change the initial position of the piston 56 within the small diametered bore 52 of the hydraulic chamber. in order to adjust the sleeve position, the tooth must be removed from the mandrel 40 so that the mandrel can be rotated. A bolt 67 or the like is provided on the lower part of the tooth to rernovably attach the tooth to the mandrel. A recess in the bottom of the tooth receives the upper end of the mandrel. A flat 73 is formed on one face of the tooth, which flat provides a mating surface with the front lip of the bucket. The mating flat surfaces prevent the mandrel and piston from rotating and thereby inadvertently adjusting the position of the stop sleeve 54.

in the operation of the apparatus described in H0. 3, a load of sufficient magnitude, when imparted to the upper end of the tooth 38, causes the piston 56 to move downwardly within the hydraulic chamber 46 which is filled with a hydraulic fluid. in order for the piston to move downwardly, fluid must flow from the bottom side of the piston through the restricted fluid flow path between the piston and the shoulder to the upper side of the piston. This restricted passage of fluid permits a controlled and relatively slow rate of movement of the piston and tooth downwardly. Upon moving a predetermined distance, the piston 56 enters the large diameter portion 44 of the housing bore below the shoulder 50, whereupon the movement of the piston and tooth is permitted to accelerate. This in turn permits the bucket and stationary teeth 34 to move in an upward direction at a rapid and accelerated rate. The statio nary, tough teeth 34 are thus impacted rapidly against the hard material embedded within the formation be excavated to cause a breaking or loosening of the hard material, and thereby permit its removal from the earth. When the hard materials have been passed by the bucket teeth the system restores the movable teeth to their normal operating condition. The compression spring 62 tends to force the piston 56 upwardly within the hydraulic chamber. Passageways 58 and check valves 60 permit movement of fluid from the upper side of the piston to the lower side so that the piston may be rapidly restored to its initial position to facilitate a subsequent jarring operation.

When it is desired to adjust the time required to operate the trip device of the hydraulic mechanism, the sleeve 54 may be moved longitudinally within the bore 52 by rotation of the piston. The mechanism may be calibrated prior to its use so that the time required to move the piston from the small diametered bore under a prescribed load may be known. Appropriate indicia 71 are provided on the mandrel, which indicia correspond to the top of the shoulder 49 on the housing to provide an a indication of the time required to trip the jar mechanism when the piston is in such position.

FIGS. 5A and 5B illustrate a device for protecting the stationary teeth 34 on the bucket from contact with earth materials during normal excavating operations. The apparatus includes a pair of pivotally mounted, horizontal shields or plates 36, which are positioned over each of the teeth 34, during normal operations. Each of the shields is pivotally attached, along its outer longitudinal edge, at 64 to the sides of the downwardly movable teeth 28 as shown in FIG. 5A. A helical torsion spring is provided along the pivotal axis of the shield. Torsion springs are designed to offer resistance to a turning moment at right angles to the coil body. The load applied to such springs tends to wind the coil body. Such springs are generally tightly wound helical springs sometimes commonly referred to as hinge springs. in the present application, one end of the helical spring is attached to the pivotal axis 64, while the other end is lapped over the top ofthe plate 36. Thus upward movement of plate 36 as shown in H0. 53 further loads the spring and upon downward movement of plate 36 the overlapping end of the spring will move the plate 36 down to its position covering the tooth 34. FIG. 5A shows the stationary tooth 34 and movable tooth 28 from a side view with the movable tooth extending upwardly above the stationary tooth. The configuration of the apparatus in FIG. 5A represents the position of the respective teeth in the normal operating condition. The shields 36 are shown in a horizontal position over the stationary tooth. As the movable teeth are depressed downwardly upon encountering a hard substance, the shields cam upwardly along their inner edges on the sloping top surface 61 of the stationary tooth 34 as the movable tooth 28 recesses below the stationary tooth. Therefore in the configuration shown in FIG. 5A, the shields protect .the stationary tooth from contact with the abrasive material normally being encountered by the excavating bucket. However, upon the movable tooth encountering a hard substance, the tooth is depressed against the spring 32 and upon such movement, the shields 36 are pivoted back against the spring hinges and move downwardly to expose the stationary teeth for contact with the hard substance being encountered. When the load is removed from the teeth, the movable tooth returns to its upward position and the spring hinges move the shields back to the position shown in FIG. 5A. The shields also connect the various movable teeth on the bucket, and therefore act as a means for causing recession of the teeth at a uniform rate and at the same time. This insures that the control tooth will function to cause a jarring action when the movable teeth have sufficiently receded.

An alternative arrangement of the center jar control tooth 38 is shown in FIGS. 6 and 7. Referring first to FIG. 6, the excavator tooth mandrel 68 is shown positioned within a housing 69. An O-ring seal 70 is positioned between the mandrel and the housing, to provide a fluid seal at the upper end of the housing and thereby create a hydraulic chamber 72. The mandrel 68 extends downwardly from the tooth within the hydraulic chamber. A shoulder 76 within the interior bore of the chamber forms a small diametered bore therein. A first shoulder portion 78 on the mandrel provides a downwardly facing surface 80. An annular sleeve 82 is positioned about the mandrel below the surface 80. The upper end of the sleeve engages the surface 80 on the shoulder when the device is in the operating condition shown in FIG. 6. A second shoulder portion 83 is formed at the lower end of the mandrel, and. has an upwardly facing surface 84. An annular follower member 86 positioned about the mandrel between the second shoulder portion 83 and the annular sleeve 82. A compression spring 87 is positioned between the upper surface 84 on the second shoulder portion and an L-shaped portion 88 on the follower. Another compression spring 90 is positioned between the lower end of the mandrel and the bottom of the hydraulic chamber. A plurality of vertical splines 92 are positioned about the mandrel to maintain the annular sleeve 82 in a concentric position about the mandrel.

ln the operation of the device shown in FIGS. 6 and 7, a force is imparted inwardly against the outward end of the tooth when the tooth is contacted with materials being excavated. During the excavation of softer material, which is normally encountered by the tooth, this force is not sufficient,

when acting against the hydraulic system and the spring 90 supporting the bottom of the mandrel, to cause the tooth to recess appreciably downwardly within the housing. However, upon encountering a harder and more resistive substance within the material being excavated, the force against the tooth may become sufficiently great to overcome the force of the spring 90 and the resisting hydraulic mechanism. When this happens, the tooth and mandrel begin to move downwardly within the housing 69. The annular sleeve 82 is sized to permit a restricted flow of fluid between the annular sleeve and the shoulder 76 as indicated by the upwardly directed arrow in FIG. 6. Since the rate ofmovement of tooth 38, which is permitted by this restricted hydraulic flow and the spring 90 at the bottom of the mandrel, is less than the rate of movement permitted by the springs 32 only, which are positioned beneath the movable teeth as shown in FIG. 1, the movable teeth are maintained in intimate working contact with the material being excavated. However, if the greater than normal force acting against the movable tooth 38 lasts for a sufficient duration, the sleeve 82 is permitted to move downwardly far enough to extend below the lower end of shoulder 76 within the hydraulic chamber. This, in turn permits a rapid flow of fluid past the sleeve into the upper part of the hydraulic chamber. The subsequent rapid downward movement of the tooth of course permits the housing 69 to move upwardly in an opposite direction at the same rapid rate. This brings the stationary teeth 34 into a jarring impact with the material which is providing a resistive force to the excavating operation. I 1 j Whenthe hard material has been broken, and the load is decreased on the control tooth 3%, the spring 90 at the lower end of the mandrel is sufficiently strong to cause an upward movement of the mandrel and the tooth. As the mandrel moves upwardly within the housing, the hydraulic fluid flows in the opposite direction, and is bypassed around the sleeve which depresses the follower spring 87 to provide such a bypass flow route. This permits a rapid recovery or movement of the mandrel 68 upwardly within the housing 69. As the annular sleeve 82 enters the restricted portion of the hydraulic chamber opposite the shoulder 76, fluid flow is permitted between the upper end of the sleeve and the downwardly facing surface on the first shoulder portion 78 of the mandrel as shown by the arrows in FIG. 6. When the mandrel has reset within the chamber, and fluid flow has ceased, the follower spring 87 forces the annular sleeve 82 against the downwardly facing surface 80 on the first shoulder portion. The device is then ready for a subsequent ready for a subsequent jarring operation. The jar mechanism is designed to reset in the time it would normally take the bucket 18 to revolve to a position bringing it once again into contact with the earth formation being excavated.

While the excavating apparatus disclosed herein has been described in conjunction with a bucket wheel excavator, it is readily seen that such a jarring apparatus would have application to other types of earth handling devices. In addition, while particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

lclaim:

1. In an apparatus for excavating earth materials, including bucket means for carrying earth materials and teeth thereon for severing the earth materials, an improvement for excavating unusually hard materials, the improvement comprising: at least one movable and one nonmovable tooth on said bucket means; and hydraulic means for permitting controlled movement of said movable teeth relative to said bucket means in response to a load applied to said movable-teeth, said hydraulic means including; a mandrel connected to a bucket tooth and movable within a hydraulic chamber; delay means for preventing rapid movement of said mandrel within said chamber; and means for rendering said delay means ineffective to prevent such rapid movement.

2. The apparatus of claim 1 wherein said hydraulic means further includes said mandrel having a portion forming a piston, a hydraulic chamber receiving said piston, said chamber having a first portion along its length for slowly passing fluid from one side of said piston to the other in response to the movement of said piston in said chamber; said chamber having a second portion along its length for rapidly passing fluid from one side of said piston to the other in response to the movement of said piston in said chamber; and selectively operable means in said hydraulic means for rapidly passing fluid from the other side of said piston to said one side when said piston is in said first portion of said chamber.

3. The apparatus of claim 2 wherein the position of said first portion of said chamber is adjustable.

4. The apparatus of claim 1 wherein said movable tooth is normally extended above said nonmovable tooth for severing earth materials of usual hardness, said movable tooth being retractable below the height of said nonmovable tooth, said hydraulic means being effective to bring said nonmovable tooth into a jarring impact with the earth materials when said movable tooth has been contacted by unusually hard materials.

5. The apparatus of claim 4 and further including means for covering said nonmovable tooth during normal excavating operations.

cludes a pair of normally horizontal plates each pivotally connected to said movable tooth and pivotal to a vertical position when said movable tooth is retracted. 

